astronomy

HAT-P-11

HAT-P-11 is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand HAT-P-11 rather than just read about it. In short: HAT-P-11, also designated GSC 03561-02092 and Kepler-3, is a metal-rich orange dwarf star with a planetary system, 123 light-years (38 parsecs) away in the constellation Cygnus. This star is notable for its relatively large rate of proper motion.

Key takeaways

HAT-P-11 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HAT-P-11 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HAT-P-11 from memory before moving on to harder problems.

Reference excerpt

HAT-P-11, also designated GSC 03561-02092 and Kepler-3, is a metal-rich orange dwarf star with a planetary system, 123 light-years (38 parsecs) away in the constellation Cygnus. This star is notable for its relatively large rate of proper motion. The apparent magnitude of this star is about 9.6, which means it is not visible to the naked eye but can be seen with a medium-sized amateur telescope on a clear dark night. The age of this star is about 6.5 billion years. The star has active latitudes that generate starspots. The spots are similar in distribution to those on the Sun, but HAT-P-11 is a more active star and has a starspot coverage approximately 100 times greater than the Sun. The star appears to have an unusually small radius, which can be explained by the anomalously high helium fraction.

Planetary system

An exoplanet, designated HAT-P-11b, was discovered by the HATNet Project using the transit method, believed to be a little larger than the planet Neptune. The planet orbits out of alignment from the star's spin axis, with an obliquity of about 100°. This star system was within the field of view of the Kepler Mission planet-hunter spacecraft. Water vapor and ammonia have been detected in the atmosphere of HAT-P-11b. A trend in the radial velocity measurements taken to confirm the planet indicated a possible additional body in the system. This was confirmed in 2018 when a second planet, HAT-P-11c, was detected on an approximately nine-year orbit. In 2020, an astrometric detection of HAT-P-11c was published, along with Pi Mensae b, allowing its inclination and true mass to be determined. Multiple 2024 studies present conflicting results about HAT-P-11c. One study suggests that the radial velocity variations attributed to HAT-P-11c may actually be caused by a magnetic activity cycle of the star. If this is the case, an outer planet may still exist given the evidence for one from astrometry, but farther from the star and with a different mass than previously thought. Another study instead claims further confirmation of the previously proposed planet. A third paper, published in response to the first, also corroborates the planetary nature of HAT-P-11c based on additional radial velocity data.

Worked examples

Example 1 — a first encounter with HAT-P-11

Start with the simplest possible case. Write down what HAT-P-11 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to HAT-P-11 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about HAT-P-11 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of HAT-P-11

In research: HAT-P-11 appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses HAT-P-11 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: HAT-P-11 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cygnus (constellation), Durchmusterung objects, Hipparcos objects, so understanding it makes those chapters shorter.
In everyday life: Look for HAT-P-11 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study HAT-P-11 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HAT-P-11 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain HAT-P-11 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HAT-P-11 in simple terms?

Why does HAT-P-11 matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study HAT-P-11?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on HAT-P-11.